Crosstalk, the unwanted transmission of signals between communication channels, in the context of hearing testing means that an unwanted audible signal is present on the inactive channel. Crosstalk occurs when power leaks from one channel to the other in systems where channels are not fully isolated (see FIG. 1).
ANSI/ASA S3.6-2010 regulates the maximum allowable levels of crosstalk for a compliant audiometer. According to this standard, crosstalk must either be less than 0 dB HL (which means that is not detectable by an average person with normal hearing) or at least 70 dB SPL quieter than the signal on the active channel.
While purpose-built audiometers meet this standard through the use of hardware designed to electrically isolate the left and right channels, a software audiometer running on a computer or mobile device needs to take extra steps in order to meet the standard. A common approach is to augment the computer or mobile device with external hardware, usually called a DAC, that is custom-designed to generate sound in accordance with the ANSI standard.
The present invention, however, describes methods of implementing a crosstalk-cancellation system entirely through the use of novel software that allows for the use of audio hardware that does not fully isolate the left and right channels. In addition, through the teachings of the present invention, it is also possible to build equivalent external hardware that is designed to remove crosstalk from an audio system using the same basic novel technique as described herein.